There have been many attempts at producing a female contraceptive that can remain in place for long periods of time without the need for removal.
The five basic types of female contraceptives now on the market are the diaphragm, the contraceptive pill, containing estrogen or progesterone, contraceptive foaming agents, cervical caps and intra-uterine devices or I.U.D.'s. Diaphragms are reliable but must be continually removed each day; contraceptive pills reportedly have various undesirable side effects, including reports of carcinogenic damage to gall bladder and liver; foams fail to foam in many women and in any case are only reliable for one day at the most; I.U.D.'s are reliable but their reported side effects including excessive bleeding, possible sterility and other effects have lessened their desirability. Cervical caps are effective but must be removed every month for menstruation to take place. Moreover, many females have deformed cervices and cervical caps simply will not fit over such cervices.
The desire then has been to develop a contraceptive which could be left in place for a long period of time, two months to two years or more without any undesirable effects.
There have been attempts over the years to produce such a cervical cap. The desire was to produce a cervical cap that had a one-way valve so that discharge from the uterus through the cervix could pass outwardly into the vagina without sperm being able to penetrate the valve and enter the uterus. Two attempts are shown in U.S. Pat. Nos. 2,836,177, Sells and 3,952,737, Lippert, et al. Both of these cervical caps securely hold the cap to the cervix; the thought was apparently that if it were not securely held it would slip off. The Sells patent mentions that the cap is shaped so as to snugly fit upon and embrace the cervix, whereas the Lippert et al patent describes a device which is clamped or securely affixed to the cervix. The device includes grooves or flanges and an "O" ring to effect the fastening. The patent even describes the use of a bladder between the cap and the cervix to more securely hold the cap to the cervix. A secure hold apparently appeared to be a most desirable technique to prevent the cap from slipping off the cervix. Just the opposite is actually the case; holding the cap securely to the cervix will cause deterioration of the cervix including possibly gangrene and such infections as cervicitis and similar disorders. The cervix can withstand a reasonable amount of contact for a very short period of time, possibly up to a month; however, much beyond that period if anything is held tightly to the cervix, it will result in deterioration of the cervix.
Another reason why the prior art cervical caps with valves were held so tightly to the cervix was probably an attempt to duplicate the fit of the non-valve cervical caps; these caps had to be removed each month so that menses could take place. The caps held onto the cervix by suction, which was very often so great that air had to be introduced between the cap and the cervix to break the seal in order to remove the cap. However, even with these caps if they remained in place for more than one month cervical deterioration would take place.
Another problem with the prior art cervical caps with valves was that the cervix on many human females does not project very far. On these women, it is impossible to hold any cervical cap in place because the cervix does not extend far enough for the cap to be attached. Even the non-valve cervical caps could not be secured to these women. Also many women have deformed cervices, such as where one of the lips, the posterior lip, for example, is substantially longer than the anterior lip. This deformation as well as other irregularities in shape make it impossible to secure any cap to these women.
Another problem with cervical caps having valves, is that it is most important that the valves be constructed so that the distance between the entrance to the valve and the cervix be as great as possible so that if any semen enters the valve the distance it has to travel is so great and travel so difficult that it will not succeed in reaching the cervix. It is also important that the valve be constructed so that clots of blood or large clumps of material cannot wedge themselves in the entrance of the valve to hold the valve open so that semen can enter.
Thus the desire is to produce a cervical cover with a valve which fastens by holding securely to the vaginal wall surrounding the cervix without applying any significant pressure to the cervix, and which also has a path from its entrance to the entrance to the cervix which is so long and tortuous that if any semen accidentally entered the valve it could not reach the entrance to the cervix in the live condition.